Toes, Foot, Calcaneus, Ankle and Lower Leg

Foot and Ankle Anatomy

The foot has 26 bones: 14 phalanges, 5 metatarsals and 7 tarsals. The tarsals are the calcaneus (heel bone), talus, navicular, cuboid and three cuneiforms. The ankle mortise is a box-shaped joint formed by the distal tibia with its medial malleolus, the distal fibula with its lateral malleolus, and the dome of the talus that fits between them. The lateral malleolus lies about 1 cm posterior to the medial malleolus, which is why a true AP does not open the whole mortise. The base of the fifth metatarsal has a tuberosity that often fractures in inversion injuries, and the sustentaculum tali is a shelf on the medial calcaneus that supports the talus.